1. Field of the Invention
The present invention relates to a technology to improve the working efficiency, for example, in creation of a numerical analysis model from a computer aided design (CAD) model to be analyzed.
2. Description of the Related Art
CAD is widely used in design of parts and products. Methods of practically using three-dimensional CAD models (hereinafter abbreviatedly referred to as CAD models) include analysis using a finite element method. Since it takes longer calculation time to practically use the CAD models in the analysis if complicated geometries and/or minute geometries exist, geometry simplification (hereinafter abbreviatedly referred to as simplification) is generally performed to alter the complicated and/or minute geometries into simple geometries keeping a certain calculation accuracy level.
The following technologies in related art are known as methods of efficiently simplifying multiple similar geometries that exist in a CAD model and that are unnecessary for simulation. Japanese Patent Laid-Open No. 2008-040921 discloses a technology in which meshes are created on the surface of a CAD model, the surface meshes are grouped into partial surface meshes, similar partial surface meshes are extracted from the partial surface meshes resulting from the grouping, and the extracted similar partial surfaced meshes are replaced with simplified surface meshes. In the technology disclosed in the Japanese Patent Laid-Open No. 2008-040921, specifically, the angle formed by the normal vectors of adjacent meshes is used as a threshold value to create the partial surface meshes. Then, the distance between the centroids of the surface meshes composing the partial surface meshes and the angle formed by the normal vectors of the surface meshes are accumulated with the areas of the surface meshes to create a histogram. Similar partial surface meshes are extracted from feature values calculated on the basis of the histogram and the extracted partial surface meshes are replaced with the same simplified mesh. Japanese Patent Laid-Open No. 2000-331194 discloses a technology in which a simplification method that is recorded is read out to perform the same simplification process again. In the technology disclosed in the Japanese Patent Laid-Open No. 2000-331194, when the geometry of a CAD model is changed, a simplification process recorded before the geometry of the CAD model is changed is read out from a database and the readout simplification process is applied to the CAD model subjected to the geometry change.
However, since the surface meshes cannot often be created for a CAD model having a complicated geometry and/or a minute geometry with the technology disclosed in Japanese Patent Laid-Open No. 2008-040921, it is not possible to apply the technology. In addition, the size or geometry of the surface meshes may be varied depending on, for example, the geometry of the CAD model and/or the positional relationship thereof. Accordingly, setting the angle formed by the normal vectors of adjacent meshes, which is used as the threshold value for the formation of the partial surface meshes, to a lower value causes many minute partial surface meshes to be formed to complicate the subsequent processing. In contrast, setting the above angle to a higher value causes coarse partial surface meshes to be formed. In this case, features that should be grouped into different partial surface meshes are recognized as the same partial surface mesh to complicate the subsequent processing.
The simplification process that is performed before the geometry of part of the CAD model is changed is read out and the readout simplification process is applied to the CAD model subjected to the geometry change in the technology disclosed in Japanese Patent Laid-Open No. 2000-331194. Accordingly, it is necessary to separately perform the simplification for other parts and other features in the same part. In the present situation, in order to simplify multiple similar geometries that exist in a CAD model and that are unnecessary for simulation, a user manually performs the simplification or the geometry change while visually confirming the similar geometries. Accordingly, there is a problem in that it takes a lot of effort and time to create a simplification model.